More than 50 homeowners and businesses around the state are showing off their renewable energy systems to all comers this weekend. Friday night, plug-in cars will be on display, along with a discussion of how plug-ins can work with renewable energy sources.

"If you're producing your own clean power, charging up car, you'll save a lot of money on gasoline, and that might allow you for example to pay back the cost of a solar photovoltaic system within five or seven years," said Christopher Charles, who is helping organize the program.

Charles said even though energy prices have come down in the last year, people are eager to learn about renewable sources of power.

"There is a growing interest still as people become more and more concerned about emissions from particularly coal-fired power plants," he said. "That's where about two-thirds of our electricity comes from in Minnesota, and as people become aware of the very serious implications of climate change.

The electric-car program is at 7:00 p.m., at Rapson Hall on the east bank campus of the U of M.